Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Master Credit Facility - USD ($)	Jun. 30, 2020	Mar. 31, 2020
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000	$ 8,000,000,000
Commercial paper	(2,480,000,000)
Outstanding letters of credit	(47,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	5,392,000,000
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,500,000,000
Commercial paper	(389,000,000)
Outstanding letters of credit	(3,000,000)
Available capacity under the Master Credit Facility	1,108,000,000
Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,250,000,000
Commercial paper	(323,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity under the Master Credit Facility	925,000,000
Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	800,000,000
Commercial paper	(156,000,000)
Available capacity under the Master Credit Facility	644,000,000
Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(79,000,000)
Available capacity under the Master Credit Facility	521,000,000
Duke Energy Indiana
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(150,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	369,000,000
Piedmont Natural Gas
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(135,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity under the Master Credit Facility	463,000,000
Duke Energy (Parent) | Proceeds loaned to subsidiary registrants
Line of Credit Facility [Line Items]
Commercial paper	(625,000,000)
Duke Energy (Parent) | Duke Energy (Parent)
Line of Credit Facility [Line Items]
Facility size	2,650,000,000
Commercial paper	(1,248,000,000)
Outstanding letters of credit	(40,000,000)
Available capacity under the Master Credit Facility	$ 1,362,000,000